Method of making edge reinforced tubes used in forming reinforced fiber drums



Sept 29, 1964 H. A. BERGsTRoM METHOD OF MAKING EDGE REINF ORCED TUBES USED FORMING REINF'ORCED FIBER DRUMS Original Filed Feb. 5, 1958 HAROLD A. BERGSM'OM United States Patent O "ice 3,151,012 METHOD F MAKING EDGE REENFURCED TUBES USED iN FRMNG REENFRCED FIBER DRUMS Harold A. Bergstrom, Van Wert, Ohio, assignor to Continental Can Company, Inc., New York, NX., a corporation of New York Original application Feb. 5, 1958, Ser. No. 713,341, now Patent No. 2,989,218, dated .lune 20, 19ml. Divided and this application Dec. 6, 1960, Ser. No. 74,172

6 Qlaims. (Cl. 156-484) This invention relates to new and useful improvements in the making of heavy duty liber drums of a large capacity and especially adapted for storing and shipping liquid or semi-liquid products, and more particularly involving an improvement over my Letters Patent 2,775,- 384, issued December 25, 1956. This application constitutes a division of my copending application for U.S. Letters Patent, Serial No. 713,341, filed February 5, 1958, now Patent No. 2,989,218.

Although the drum disclosed in the abovemcntioned patent is satisfactory for the purpose intended, it has been found through various tests that utilization of an inner metal ply extending the entire length of the body wall in the manner disclosed in the abovementioned patent, and the producing of the body wall by the method disclosed therein can be improved upon through the utilization of the method to be described in detail herein.

The liber tube from which a drum of the character stated is formed, even in the absence of a reinforced ply therein, has been found through tests to have considerable compression strength. Formation of the chimes to include an annular groove adjacent the upper and lower ends of the tube will considerably decrease the compression strength of the tube, possibly as much as sixty percent. The filled drums are generally stacked three, four and sometimes live high so that the bottom drum rnust support a considerable Weight. Additionally, a drum eX- posed to relatively high humidity conditions results in the fiber board from which the body wall is constructed becoming somewhat weakened and reducing the stacking strength to a considerable degree. It has been found that the reinforcing of the chime area of a drum by means of a circumferential partial ply of relatively thin sheet metal at the chime area appreciably increases the stacking strength of the drum and maintains the stacking strength since the sheet metal will not be affected during a high relative humidity condition.

lt has been further found during actual vibration and shipping tests that in a lled drum, in the absence of a reinforcement ply at the bottom chime, considerable rigidity of the drum is lost due to the formation of the chime since the paper fibers are distorted in the body wall. During the tests conducted, considerable movement was observed immediately above the bottom chime even though the liquid tight seal at the bottom chime was not affected. Thus by utilization of a ply of relatively thin metal in the body walls and forming the same to the contour of the chime, the rigidity at this critical area was substantially increased.

In the shipping and handling of ber drums, it has been observed, the most vulnerable areas susceptible to being punctured are immediately above and below the respective bottom and top metal chimes. In carload shipment, humping and vibration of the cars will tend to cause the drums to tip over, this being especially true in refrigerator cars where Athe bottom of the car generally includes wood slats between which the bottom chime of the drum, as it tips, may become engaged, and during humping, the top portion of the drum tends to tip forward. When this tipping occurs it may be severe enough so that the top or 3,151,012 Patented Sept. 29, i954 bottom chimes of adjacent drums are disposed upon one another and upon the next impact the drums will not be resting adjacent to one another so that the metal chimes will absorb the force of the impact. When such a situation occurs, the force of the impact will be absorbed by the ber of the body wall above or below a respective bottom or top metal chime. However, if the body wall of the drums is reinforced by utilizing a partial metal ply of the character involved, puncture resistance of the drum will be improved at the previously mentioned vulnerable areas.

When filled drums are being handled for the purpose of unloading a truck or freight car and are dropped off of the loading dock, for example, the vulnerable points of damage in the sidewall have been found through tests to be immediately above the bottom or below the top metal reinforced chimes. When the drum is dropped, it is distorted, and, starting at the point of impact, it tends to assume an elliptical shape so that at approximately fteen to thirty degrees from the point of impact, the ber sidewall is placed under tension. The hydraulic pressure developed by the liquid in the drum tends to thrust outwardly, causing the sidewall to rupture at these points, resulting in vertical tears that will generally extend from one to two inches from the chime. By embedding a partial ply of a relatively thin sheet metal at these critical areas, the tensile force resulting during an impact of the character involved is absorbed or transmitted to the reinforcing ply and therefore tears or ruptures in the wall at the chime area are obviated.

When forming a tubular reinforced drum body in the manner disclosed in my Letters Patent 2,775,384, a leading and trailing sheet of stock material is taped to an intermediate sheet of metal and ultimately wound on a winding mandrel. The tube ultimately formed in this manner, although satisfactory for the purpose intended, requires a considerable amount of labor to be expended in preparing the material to be wound, and special attention must be given to the manner in which the leading and trailing sheets are secured to the intermediate reinforcing sheet of metal.

A primary object of this invention is to provide a novel method for producing reinforced drum body structures of the character stated, affording all of the advantages relative to reinforcing the critical chime areas of a finished heavy duty liber drum, the novel method involved comprising steps which are simple and may be performed in an economical and expeditious manner, producing an article which is satisfactory and practical for the purpose intended.

A more specific object of the invention is to provide a method of the character stated comprising the steps of securing on a continuous length of stock material a pair of strips of thin gage sheet metal parallel to the opposite side edges of the stock material, and convolutely winding said stock material on a winding mandrel forming one or more inner and outer plies with said strips of metal forming a circumferential partial ply at the upper and lower ends of said convoluted tube.

A further object of the invention is to provide a method of the character stated comprising the steps of securing on a continuous length of material wide enough to form at least two tubes a plurality of parallel pairs of thin gage sheet metal strips approximately equal in length to the finished circumference of a finished tube and with the strips of each pair spaced inwardly of the ends of a finished tube in which they are to be incorpo-rated, convolutely winding the stock material on a winding mandrel forming and one or more inner and outer plies with said pairs of strip of metal forming a circumferential partial ply adjacent the ends of each convoluted tube between the adjacent pair of the sheet metal strips to form a pair of convoluted tubes reinforced adjacent their ends.

With the above and other objects in view that will hereinafter appear, the nature of the invention will be more clearly understood by reference to the following detailed description, the appended claims and the several views illustrated in the accompanying drawing.

In the drawing:

FIGURE l is a view showing diagrammatically the method of forming from a stock blank a tubular cylinder incorporating partial metal plies adjacent the blank ends thereof with intermediate portions of the material being broken away.

FIGURE 2 is a top plan view of the blank stock material prior to the same being wound to form the tubular body of adrum.

FIGURE 3 is a plan View similar to FIGURE 2, showing the manner in which the blank stock material may be prepared for the purpose of forming a pair of tubular body members simultaneously.

FIGURE 4 is a fragmentary enlarged vertical section through the bottom portion of a drum showing the sheet metal partial ply embedded therein adjacent the chime of the drum and the body wall and bottom heading joined by a liquid tight beading. FIGURE 5 is a fragmentary enlarged section through the upper portion of the body wall of the drum showing the sheet metal partial ply embedded therein adjacent the chime of the drum.

FIGURE 6 is a Vertical section through a formed cylinder having a partial metal ply embedded therein, which cylinder is to form the body wall of the improved reinforced ber drum.

FIGURE 7 is a fragmentary horizontal section through the completed wall of a portion of the improved drum at the position of one of the metal reinforcing inserts and showing how the ends of the insert may be overlapped.

Referring to the drawing in detail, indicated at 1, is a continuous strip of stock material, iberboard or the like, which will be wound on a suitable winding mandrel 2 to form a convoluted tube used as the body of a reinforced heavy duty tibre drum, Secured on the upper surface 3 of the strip or sheet of stock material 1 are a pair of relatively light gage strips of sheet metal 4 and 5 parallel to each other and the respective adjacent side edges 6 and 7 of the stock material and preferably but not necessarily inwardly of said side edges. The strips of sheet metal are secured by means of Ia suitable adhesive material as indicated at 8 which may be initially coated on the strips of sheet metal and may be of the pressure-sensitive type, if preferred. When the stock material 1, after the strips of sheet metal have been secured thereon, has been rolled on the mandrel 2, a convoluted tube will be formed incorporating .a series of outer plies 9, inner plies 1u and the partial metal ply insert as seen at 4 in FIGURES 6 and 7 and provided by the endwise spaced metal strip inserts. A suitablev impervious liner 11 may be incorporated in the tube.

Details of the arrangement of the inner and outer plies in relation to the beforementioned partial ply insert i may be readily observed in FIGURE 7, it being noted that the incorporation of the metal ply formed from the metal strips 4 and 5 will not disturb the continuity of the stock material 1 thus retaining the normal liber strength of such material.

Referring to FIGURE 3, the strip of stock material as indicated at 15 will be of suiiicient width to form a pair of tubular elements to be used in constructing a pair of fiber drums. Parallel strips of light gage sheet metal as indicated at 16 and 17 will be secured on the stock material 15 adjacent the respective side edges 18 and 19. A second pair of strips of sheet metal 2t? and 21 will be secured in spaced parallel relationship adjacent to and spaced from the longitudinal center 22 ofthe stock material. After the stock material 15 has been wound on a suitable mandrel 'to provide a convoluted tube, the tube will be split between the sheet metal strips Ztl and 21 thus providing a pair of tubular body wall elements used in forming a pair of reinforced liber drums.

While the spacing of the metal strips from the side edges has been stressed herein, it is to be understood that it is not absolutely essential that said strips be located inwardly from the side edges as shown in FIGURES 2 and 3. The reason for the preference that the metal strips be spaced inwardly as stated is so that when the wound tube is slit to proper height, the slitter knives will not have to cut through the metal. Another reason why it is preferred not to have the metal inserts go to the ends of the tube is because in its reinforcing function, it would do no good at the extreme ends and projection thereof to the end extremities would merely result in wastage of metal.

It is to be understood that when either a single drum is formed as in FIGURE 2, or two or more drums are to be formed as in FIGURE 3, the practice is always to slit the tube to the exact required height prior to continuing the remainder of the assembly and formation. It is impractical to convolutely wind a tube so accurately that the end edges thereof will be perfectly square, since any variations in caliper of paperboard will cause the paperboard to weave back and forth. In order to get square edges and a tube of accurate length, it is therefore the practice to perform a slitting operation in which the slitter knives are located exactly to the dimensions of the tube height required. The slitter knives will then cut a sharp square edge such as is shown at 6 in FIGURE 6. At the outer edges of the tube, an allowance is usually made for about one-quarter to three eighths inch trim loss. Obviously in FIGURE 3 Where the slitting is to be included along the dotted center line 22, only a single slitter knife will be necessary in the center and then one knife at each outer edge will trim the tubes to proper length.

In FIGURE 7 the metal reinforcing strip is shown as of a length for very slightly overlapping at its ends. This arrangement may pertain, or there may be no overlapping of the metal strip ends. Actually, effort is made to have an exact length of metal strip so that there is n'o overlap, or even to run about one thirty-second of an inch less than a full meeting at the end edges of the strip. This is done primarily to ease the load on the forming dies because obviously there would be an extra strain placed on the dies at a point of overlapping.

Thus by means of a simple and expeditious method one or more tubular body elements may be formed to be used in a reinforced fiber drum for attaining the desirable advantages particularly as set forth in the objects of invention and for reducing the potential damage which might occur at the chime areas in the nished drums.

The tubes formed by the method mentioned above are used in making up the improved heavy duty reinforced ber drums. The usual chime ring or collar 25, see FIGURE 5, is applied to the upper end of the tube, after which the body wall is beaded inwardly as indicated at 26 and the chime member is formed over the upper edge of the body wall as indicated at 27, as by rolling or crimping. It will be noted that the lower edge 28 of the chime member terminates above the lower edge 29 of the reinforcing metal ply 4 to afford the desirable protection in this critical area, especially during stacking, transit and unloading of the drums when they are filled with liquid.

As shown in FIGURE 4, the bottom heading of the drum may be construed to include a filler disk 30, a liner 31, a metal tray 32 and also the iiberboard disk 33 which extends across the bottom of the drum in the manner illustrated. Optionally, the metal tray 32 may be omitted. The protective liner 11 and liner 31 may be coated with a liquid resisting material such as polyethylene or any other type of suitable coating which will resist the penetrating or corrosive effect of materials which may be packaged, and will be strong and flexible enough to withstand the final forming of the body as well as p1 L? various shipping abuses. A metal chime member or band 34 is placed on the body portion after which the chime, body wall and the flanges of the body heading are all formed into a very tight bead 35 which is formed against the bottom heading and clamps the same tightly against the shoulder 36 formed by inwardly beading the chime member 34 and the body Wall in the manner previously described with respect to the upper bead 26. it is to be understood that when the pre-formed metal tray 32 is omitted, the various components 30, 31 and 33 are glued and registered into correct relationship with one another and this heading is then positioned into the cylindrical tube or drum body prior to mounting the rnetal band 34 and going through the final forming operations; therefore the tube actually serves as a fixture for pre-forming the bottom heading into the tube prior to the final operations.

It will be noted that the metal ply 5 embedded in the body wall extends upwardly above the upper edge 327 of the chime member 34, terminating thereabove as indicated at 3S and providing adequate protection for this critical area of the drum.

Thus there has been disclosed a readily manufactured reinforced fiber drum especially adapted for storing liquids or semi-liquids, particularly strengthening the drums at extremely critical areas, the drums incorporating tubular body members produced in an expeditious manner by a novel method.

In addition to the saving of the metal as against winding a thin ply of steel the full length of the tube as shown in Patent 2,775,334, this new method not only locates the steel at the most vulnerable point of the drum, but also permits fabricating from relatively narrow widths of steel. Light gage steel cannot be procured in too Wide a width, approximately 36 being the widest available. Even a large drum run one up, as in FlGURE 2, presents a problem if the drums are taller than steel is available. Obviously, it would be impossible to run large drums two up since it is possible to Wind the paperboard up to seventy-five and one-half inches wide and light gage steel probably never will be available that wide. In the method shown in FIGURE 3, it would be possible to use one wider strip of metal in place of the two strips 20 and 21 since we would still be talking of a sheet only 12 or so wide. The slitting along line 22 would then obviously be made through this center ply of steel.

It is obvious that changes in the steps in the method of forming the construction may be made without departing from the spirit of the invention as set forth in the appended claims.

I claim:

1. A method of reinforcing edges of a convoluted fiber tube for use in a cylindrical fiber drum comprising the steps of first securing on a continuous length of stock material a pair of strips of thin gage sheet metal parallel to the opposite side edges of the stock material, and thereafter convolutely winding said stock material on a winding mandrel forming at least one inner and outer ply with said strips of metal forming a circumferential partial ply at the upper and lower ends of the convoluted tube.

2. A method of reinforcing the edges of a plurality of simultaneously formed tubes for use in the manufacture of cylindrical fiber drums comprising the steps of securing on a continuous length of material wide enough t0 form at least two tubes a plurality of parallel pairs of thin gage sheet metal strips approximately equal in length to the finished circumference of a finished tube and with the strips of each pair placed to be disposed at the ends of a finished tube in which they are to be incorporated, convolutely winding the stock material on a Winding mandrel forming at least one inner and outer ply with said pairs of strips of metal forming a circumferential partial ply at the ends of each convoluted tube length, and cutting the multiple tube length convoluted tube between an adjacent pair of the sheet metal strips to form a pair of convoluted tubes reinforced adjacent their ends.

3. A method of reinforcing edges of a convoluted fiber tube for use in a cylindrical fiber drum comprising the steps of first securing on a continuous length of stock material a pair of strips of thin gage sheet .metal parallel to and inwardly of the opposite side edges of the stock material, and thereafter convolutely winding said stock material on a winding mandrel forming at least one inner and outer ply with said strips of metal forming a circumferential partial ply adiacent each of the upper and lower ends of said convoluted tube.

4. A method of reinforcing the edges of a plurality of simultaneously formed tubes for use in the manufacture of cylindrical fiber drums comprising the steps of securing on a continuous length of material wide enough to form two tubes a plurality of parallel pairs of thin gage sheet metal strips approximately equal in length to the nished circumference of a finished tube and with the strips of each pair spaced inwardly of the ends of a finished tube in which they are to be incorporated, convolutely winding the stock material on a winding mandrel forming at least one inner and outer ply with said pairs of strips of metal forming a circumferential partial ply adjacent the ends of each convoluted tube between the: adjacent pair of the sheet metal strips to form a pair of convoluted tubes reinforced adjacent their ends.

5. A method of reinforcing edges of a convoluted tube for use a cylindrical drum comprising the steps of first placing and adhering a pair of strips of light gage sheet metal on a continuous length of stock material to the opposite side edges of the stool; material and in such a position that when the tube is convolutely wound the adhesive utilized to join the various plies of the stock material together also adheres the original overlying side of said metal strips to a subsequent ply of the stock mt.- terial, and thereafter convolutely winding said stock material on a Winding mandrel to form at least inner and outer plies with said strips of metal forming a circumferential partial ply at the upper and lower ends of the convoluted tube.

6. A method of reinforcing the edges of a plurality of finished tubes which are to be cut from an initial single convolutely wound fiber tube comprising the steps of placing and adhering on a continuous length of material wide enough to form at least two finished tubes a plurality of parallel thin gage sheet metal strips approximately equal in length to the circumference of a finished tube and with the strips disposed at positions which will become the ends of respective finished tubes when the initial convolutely wound tube is cut into at least two finished tubes, convolutely winding the stock material on a winding mandrel to form an initial single convolutely wound tube having at least inner and outer fiber plies with said parallel strips of metal forming separate circumferential partial plies, and cutting the thus Wound initial tube into at least two finished tubes each having a metal reinforcing partial ply at opposite ends thereof.

References Cited in the file of this patent UNITED STATES PATENTS 679,171 Jones July 23, 1901 1,215,970 Naylor et al. Feb. 13, 1917 1,504,491 Nicholson Aug. 12, 1924 2,260,064 Stokes Oct. 21, 1941 2,511,481 Schneider lune 13, 1950 2,578,667 Brennan Dec. 18, 1951 2,643,593 Lenard et al .lune 30, 1953 2,775,384 Bergstrom Dec. 25, 1956 2,966,436 Fox et al Dec. 27, 1960 

1. A METHOD OF REINFORCING EDGES OF A CONVOLUTED FIBER TUBE FOR USE IN A CYLINDRICAL FIBER DRUM COMPRISING THE STEPS OF FIRST SECURING ON A CONTINUOUS LENGTH OF STOCK MATERIAL A PAIR OF STRIPS OF THIN GAGE SHEET METAL PARALLEL TO THE OPPOSITE SIDE EDGES OF THE STOCK MATERIAL AND THEREAFTER CONVOLUTELY WINDING SAID STOCK MATERIAL ON A WINDING MANDREL FORMING AT LEAST ONE INNER AND OUTER PLY WITH SAID STRIPS OF METAL FORMING A CIRCUMFERENTIAL PARTIAL PLY AT THE UPPER AND LOWER ENDS OF THE CONVOLUTED TUBE. 